Phonograph reproducer



Feb. 4, 1930. A A THOMAS 1,745,776

PHONOGRAPH REPRODUCER Filed Jan. 23. 1926 INVENTOR '40 `The volume of sound thus produced is usuillustrative example is shown in the accom- 90 ,l ally suiicient for an ordinary room in a house panying drawings, where Patented Feb. 4,1930 1,745,776

UNITED STATES PATENT OFFICE ADOLPH A. THOMAS, F NEW YORK, N. Y.

PHONOG-BAPH REPRODUCER Application led January 23, 1926. Serial No. 83,190.

This invention relates to the art of reprorents to flow in a telephone receiver. These ducing recorded sound, and its object is to currents may be amplified or stepped up t0 provide a new and improved reproducer for increase the' volume of reproduction to the phonographs or similar acoustic machines required degree. It is recognized that each utilizing sound records for loud reproducmethod of phonographic sound reproduction 55 tion. that is, the mechanical and the electrical- The basic idea of my invention comprises has its-advantages: the mechanical method a combined electro-mechanical reproducer as requires no batteries, circuits, etc., and the a single unit capable of reproducing from electrical method permits greater acoustic a record either mechanically through a diaamplification, together with a finer regula- 60 A phragm or electrically through suitable election of volume. tromagnetic mechanism. There yis one nee- In order to combine the advantages of medle arm for actuating the diaphragm and chanical and electrical sound reproduction a secondneedlearm for operating the electric in a single machine, I have provided a coml1:5 reproducing mechanism. Either needle arm bined mechanical and electrical reproducer 65 is readily brought into playing position, as in a single unit pivotally mounted on the tone more fully explained later on. arm. This double-acting unit has two needle The acoustic reproduction of phonograph arms so arranged that the needle holders prorecords has heretofore been carried out in ject from the periphery of the reproducer two ways: irst, mechanically by means of casing at radially separated points, which 70 a diaphragm actuated by the record needle, may be 180 or 90 apart, or at any other the diaphragm vibrations being amplified convenient angle. One of the needle arms through the tone arm and horn of the maactuates a diaphragm which sends the sound chine; second, electrically by causing Vthe vibrations through a tone arm in the usual needle to operate a microphone orjan elecway. The other needle arm operates a suit- 75 tro-magnetic device mounted on the tone arm able electric reproducer which is connected for producing variable currents inja teleto or controlsaloudspeaker. The casing that phone receiver, which may be located in the carnes the parts is rotatably mounted on the phonograph cabinet or at a distance theretone arm or on the so-called goose-neck swivfrom. In this electric reproduction, the tone elled thereon. Releasable locking means on so arm is not utilized as an amplifier of sound the tone arm and casing automatically lock waves, but the telephone receiver is acoustithe casing in correct position for either neecally connected with an amplifying horn or dle arm, and yet readily permit adjustment operates through a loudspeaking diaphragm. of the casing into either of its playing posi- In phonographs utilizing mechanical reprotions. Thus, by a slight turn of the casing, 85

duction, the maximum volume obtainable is you can reproduce mechanically or electrilnecessarily limited by the maximum vibracally, as you will, from a phonograph record. tions of the needle-actuated diaphragm as The basic idea of my invention may be emampliied through the tone arm and the horn. bodied in various constructions, of which an or an apartment. But there are times when Fig. 1 shows a side view of a combined it isdesirable to obtain a greater volume of mechanical and electrical phonograph reproreproduction from a record than is possible ducer constructed in accordance with my i11- with a mechanical sound box-as, for invention, the cover of the casing being removed 95 stance, where a phonograph is played in a to show the inside; large hall or in the open. To meet this con- Fig. 2 is a cross-section approximately on dition, it has been proposed to use an electric the broken line 2-2 of Fig. 1; reproducer in which the` needle operates a Fig. 3 is a transverse view in section on line microphone or otherwise causes variable cur- 3-3 of Fig. 1; loo

Fig. 5 'shows a rear view of the reproducer casing along the broken section line 5-5 of Before proceeding with a detailed description of the drawings, I want to make it plain that the various views are shown on an enlarged scale for clearness. For the same reason, the different parts in their assembled form are not to be taken as correctly proportioned, but are purposely shown exaggerated in their dimensions.

The various parts that go to make up th1s double-acting reproducer are carried by a casing C of suitable construction nand deslgn, In the present instance,the casm consists of a back-plate 1, a cylindrical bo y sect1on 2 and a front plate or cover 3. These three parts are separably secured together any practical way, as by screws l engaging .1n bosses 5 and 6. lIhe bosses 5 are on the 1nside of the casing to engage the screws that hold the cover 3 4in place, but the rear bosses 6 are for convenience arranged outside the casing, as best shown in Fig. 5. The casing C may be formed out of light non-magnetic metal, such as aluminum or an aluminum alloy,'but it can be made of a non-metallic composition having the required hardness and strength. j p

The-cylindrical body 2 of casing C 1s provided with an annular flange 7 which forms a shallow chamber or recess 8 for mounting a vibratory diaphragm 9 ofl proper design. rllhe particular manner of supporting the dlaphragm is immaterial. In the drawm s I have shownthe diaphragm held clampe between a pair of rings or washers 10 of sounddeadening material, such. as rubber, felt, leather and the like. en the back-plate 1 is taken od, the diaphragm is accessible for inspection or removal. 'llhe center of diaphragm 9 is connected to the inner end of a needle arm 11 pivoted to the body section 2 of the casing in any practical way, as by means of bearing screws l2 mounted in a pair of lugs 13 projecting from the periphery of the casing. rllhe outer end of needle arm 11 1s 'in the form of a needle holder 14 adapted to hold phonograph needles in record-playing position. The needle arm 11 projects into the casing. through a slot 15. The annular flange 7 is slotted at that point so as not to interfere with the movements of the needle arm.

Within casing C is mounted a circular magnet 16,' preferably of the permanent type. It is convenient to secure the magnet to the circular flange 7, as by means of screws 8. Magnet 16 terminates in poles 17, which project forwardly and carry pole pieces 18, usually made of soft iron or soft steel. In the airgap between the axially aligned pole pieces 18 operates a coil 19 secured to the inner end of a vsecond needle arm 20, which is pivoted to the casing in any practical way. In the present embodiment, I have shown the outer portion of the needle arm 2O secured to a flat spring-blade 21 mounted at its ends in a air of lugs 22 projecting from the casing. he spring-blade 21 allows the needle arm 20 to vibratetransversely of the casing, and yet it firmly supports theneedle arm against any longitudinal thrust.- The spring 21, therefore, acts like a pivot and automatically restores the needle arm to normal position, so that no separate restoring and centering spring is necessary. This articular feature forms the subject matter o a copending application of mine and is not herein claimed. In a broader aspect of my invention the needle arm 20, like the other needle arm 11, may be pivotally mounted on the casing by any suitable means. 20 as needle arms, I mean broadly any practical stylus-carrying members, irrespective of the particular form of stylus used;

The coil 19, which in small and very light, may be secured to the freeend of needle arm 20 by means of a band 23, the ends of which overlap the free end of the needle arm, so that the parts may be rigidly secured together by means of a single pin or screw 24. 'llhe outer end of needle arm 20 is provided with a needle holder 25, which may be like the needle holder 142, or of any other practical construction. A slot 26 in the periphery of body section 2 allows the needle holder 20 to project into the casing. If necessary, the cover 3 of the casing may be formed with a bulge 27 to provide sullicient room for the vibrations of needle arm 20.

The resilient spring support 21 normally holds the needle arm 20 in such position that the coil 19 is in axial alignment with the pole pieces 18', so that normally the maximum flux passes through the coil. It is preferable to make the pole pieces 18 of cylindrical form and of approximately the same diameter as the internal diameter of the coil. In this construction, as the coil vibrates transversely of the pole pieces, the magnetic flux through j the coil varies correspondingly, s0 that currentl impulses are generated in the circuit of the coil. The greater thel amplitude of vibration of coil 19, the greater are the flux varialtions. Consequently, the current impulses generated in coil 19 are an electrical representation (as it were) ofthe mechanical vi- When I refer to the parts 11 and' practice is quite lconnections are well understood by electrical engineers, I need not show or describe them in detail. It is suicient that I show a pair of leads 28 connected'to the ends of coil 19. 'llhese conductors pass through a small hole in the casingto a pair of terminals or. bindmg posts 29`mounted on a small insulating disk 30, which is secured to the back-plate 1 of the casing by screws 31 or otherwise. Sincethe coil is made of very fine wire, the conductors 28 Within the casing do not interfere with the proper vibrations of needle arm 20 and coil 19. To the binding posts 29 are connected wires 32, which lead through a hole 33 in .the cylindrical hub 34 of the casing, as best shown in Fig. 5. The binding posts 29 may have wing-nuts for the ready connection and disconnection of the wires 32 without tools, as when it is desired to remove the sound box from the tone arm.

The reproducer casing is mounted in corlrect radial position on a tone arm 35, of which the outer portion is shown in Fig. 2. The hub 34 of casing C fits snugly and yet rotatably on the free end 36 of the tone arm. A suitable stop, such as an annular rib 37, limits 'the inward movement of the hub 34 .when the reproducer is inserted on the tone arm.

In order to insure the correct angular position of the reproducer on the tone arm with respect toyeach needle arm, suitable locking means is provided for firmly but releasably I locking the casing in either of its playing positions. Such locking means may be embodied in various forms, one of which is shown in Figs. 2 and 4 by way of example. The outer end of tone arm 35 is provided with a spring-finger. 38 carrying at or near its free end a lug 39 of roundedl shape. The hub 34 of the reproducer casing is provided with a pair of recesses 40 for receiving the lug 39, which fits snugly and firmly in either recess for holding the reproducer casing locked in position. The engagement between the lug and either recess is such that a slight turning force exerted on the casing is sufficient to force the lug out of therecess, so as to permit adjustment of the reproducer into the other playing position. The angular arf rangement of the locking lug 39 and the two recesses 40 is such that, when .the lug rests in one recess, the reproducer 11 is in casing in proper position without any attention on the part of the operator.

In the example shown in the drawings, the two needle arms l11 and v20 are, shown at an anglev of 180, and consequently, the recesses 40 are spaced at the same angle. It will be clear, however, that any other angular spacing of the needle arms may be used. For instance the two needlearms could be arranged at an angle of 90, vso that only one-quarter of a turn would be necessary to adjust the casing into 'position for either mechanical or electrical reproduction. v

In the broader aspect of my invention, the needle arm 20 may operate any suitable electric reproducing mechanism. The coil 19 v and the associated magnet represent only one of various electromagnetic reproducing devices that may be housed within the casing, and I therefore do not limit myself to any particular construction of electric reproducing mechanism controlled or operated by the needle arm 20.

If it is for any reason necessary or desirable to remove the reproducer lfrom the tone arm, the wires 32 are first disconnected from the binding posts 29. This is easily done by loosening the wing-nuts of the binding posts. Then the casingis given a slight twist to force the locking lug .39 out of its recess, whereupon the casing may be slipped olf the tone arm. Concealment of the wires 32 within the tone arm adds to the neatness of the phonograph as a whole.

Although I have herein shown and described a certain specific construction, I want it understood that I have done so in 'order to explain my invention fully and clearly to those skilled in the art, and not by way of restriction or limitation. The basic 4idea of my invention may be mechanically embodied in various other ways without departing from the scope of the invention as defined in the following claims. It is apparent that my reproducer may be so mounted on the supporting arm as to play either lateral-cut records or vertical-cut records. My new double-acting reproducer constitutes a unitary device on'said casing, which is adapted to be mounted on a' tone arm and adjustable to bring either mechanism into playing position.

2. As a new article of manufacture for attachment to phonographs, a casing containing acomplete mechanical and a complete -electricalreproducing mechanism, each of sald mechanisms including a stylus arm pivoted on the casing, and said casing being adapted to be mounted on a tone arm and revolved thereon as an axis to bring either mechanism into playing position.

3. As a new article of manufacture for attachment to phonographs, a casing carrying a pair of independently pivoted stylus arms, mechanical reproducingmeans carried by said casing and operated byone of Said arms, and electrical reproducing means also carried by said casin and operated bythe other stylus arm, sald casing being adapted4 to be -mounted on a tone arm so as to bring either stylus arm into playing position.V

4. 'As a new. article of manufacture for atachment to phonographs, a combined mechanical and electrical reproducercomprising vasupport, a diaphragm and electric reproducing means mounted on said support, a stylus arm pivoted on said support .ior actuating said diaphragm, and a second stylus arm pivoted on said support for operating said reproducer means, said support and all parts carried thereby being adapted to be mounted on a tone arm so that either stylus arm can be moved into playing position.

5. As a new article 'of manufacture for attachment to phonographs, a combined me chanical and electrical reproducer comprising a casing, a diaphragm and electric reproducing mechanism mounted in said casing, a pair of stylus arms pivoted on said casing for operating said diaphragm and said reproducing mechanism respectively, said casing bein adapted to be mounted on a tone arm an rotatable thereon to bring either stylus arm into playing position.

6. As a new article of manufacture for attachment to phonographs, a substantially cylindrical casing provided with two' stylus arms arranged to project from the periphery of said casing at radially separated points, a diaphragm mounted on said casing and con nected to one of said stylus arms, and electrical reproducing mechanism in said casing operated by the other stylus arm, said casing being adapted to be rotatably mounted on a tone arm to bring either stylus arm into playing position.

7. As a new article of manufacture for attachment to phonographs, a casing carrying a diaphragm for mechanical reproduction and electromagnetic mechanism for electrical reproduction, and a pair of separately movable members mounted on said casing for selectively operating said diaphragm and said mechanism independently of each other, said casing being adapted to be mounted on an arm to bring either of said reproducing Y devices into playing postion.

8. In a combined mechanical and electrical phonograph reproducer, a cylindrical casing provided with an integral interior flange arranged between the opposite ends of the casing provided with an integral flange arranged between thev opposite ends ofthe casmg to divide the same transversely into two chambers, a diaphragm mounted in one of said chambers, and. electric reproducing mechanism in the other chamber, said mechnism including a magnet secured to said flange. ADOLPH A. THOMAS. 

